Guest mamasbuick Posted April 10, 2014 Share Posted April 10, 2014 (edited) My 53 straight has a vibration issue at 45 MPH driving and at high rpm idle.Possible causes already eliminated are: not the vibration damper, or generator. The flywheel is mounted correctly according to the two drainplugs on the torque converter. Would appreciate hearing from anyone who has hada similar problem with their straight-eight. Engine was overhauled by previousowner. Other than vibration, engine runs nicely. Thanks Edited May 3, 2014 by mamasbuick (see edit history) Link to comment Share on other sites More sharing options...
trp3141592 Posted April 11, 2014 Share Posted April 11, 2014 Hi,Motor mount(s) shot? Different length bolts from torque converter to flywheel? Damaged fan belt? --Tom Link to comment Share on other sites More sharing options...
bhambulldog Posted April 12, 2014 Share Posted April 12, 2014 Engine mounting pads would be my first suspect Link to comment Share on other sites More sharing options...
JohnD1956 Posted April 13, 2014 Share Posted April 13, 2014 I would suggest removing the fan belts and running the engine for a few minutes to see if you still have the vibration. If not I would check your fan for damage first. Link to comment Share on other sites More sharing options...
avgwarhawk Posted April 14, 2014 Share Posted April 14, 2014 Tires are ok and balanced? U-joint possibly had gone bad? Link to comment Share on other sites More sharing options...
Guest mamasbuick Posted May 3, 2014 Share Posted May 3, 2014 (edited) Vibration issue update: engine motor mounts were replaced and the vibration has become less profound, but is still there at 40-45 mph. Tires were balanced, fan belt removed and tested, u-joints replaced in drive shaft as well as new rear wheel bearings. Edited May 3, 2014 by mamasbuick (see edit history) Link to comment Share on other sites More sharing options...
TexasJohn55 Posted May 3, 2014 Share Posted May 3, 2014 No fun. You will have to temporarily seperate the converter from the engine. I don't know if you can slide the converter back enough to clear the flexplate or not but you need to run the engine without the converter. If it is a balance problem, that will isolate to engine or converter. You may be able to support trans and slide back on bolts, then slide some spacers between trans and engine and snug back up after converter is clear, then run engine. If vibration goes away, try rotating converter 180* and run it. Mark converter to flexplate first before unbolting. Link to comment Share on other sites More sharing options...
60FlatTop Posted May 3, 2014 Share Posted May 3, 2014 I see from previous posts that the u-joint was replaced in 2010. What kind of history has the car had since then?Bernie Link to comment Share on other sites More sharing options...
Aaron65 Posted May 3, 2014 Share Posted May 3, 2014 Is the high-idle vibration when the car is stationary? If so, it couldn't be anything behind the torque converter in all probability.Maybe a dumb question, but is it running on all 8? Sometimes it's not all that obvious, since in reality, each cylinder in a straight 8 is only contributing maybe 15 horsepower total. Link to comment Share on other sites More sharing options...
1939_Buick Posted May 3, 2014 Share Posted May 3, 2014 Is it road speed only related or engine RPM? Link to comment Share on other sites More sharing options...
TexasJohn55 Posted May 3, 2014 Share Posted May 3, 2014 If vibration is engine or converter, it should show up at same critical rpm out of gear or in any gear, not just 45 mph.If drivetrain related or wheels, it will only show up at critical road speed and less at other speeds.If engine miss, it may be felt more or less with engine load and rpm and be quite variable.If it vibrates out of gear at a certain rpm, that may correlate to 45 mph but would need a tach to confirm if vibration always shows up at same engine rpm. Link to comment Share on other sites More sharing options...
1939_Buick Posted May 3, 2014 Share Posted May 3, 2014 If vibration is engine or converter, it should show up at same critical rpm out of gear or in any gear, not just 45 mph.Difficult to analyse with a Dynaflow. Easy if the car had a standard transmission Link to comment Share on other sites More sharing options...
Guest 53 Roady Posted May 6, 2014 Share Posted May 6, 2014 The drain plugs narrow the orientation but I think it can still mount 2 ways and one is wrong. If it weren't for the high idle I would suspect balance of the wheel mass. Maybe the wheels were balanced but the drums may be off. Keep us posted.Pat Link to comment Share on other sites More sharing options...
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